A new kind of genetically modified crop under the brand name of "Enlist" -- known by its critics as "Agent Orange corn" -- has opponents pushing U.S. regulators to scrutinize the product more closely and reject an application by Dow AgroSciences to roll out its herbicide-resistant seeds.

The corn has been genetically engineered to be immune to 2,4-D, an ingredient used in Agent Orange that some say could pose a serious threat to the environment and to human health. Approval by the United States Department of Agriculture and Environmental Protection Agency would allow farmers to spray it far and wide without damaging their crops, boosting productivity for the agribusiness giant.

Dow and its allies have insisted that their product is well tested, while industry regulators have so far overlooked critics' concerns.

"This is going to be a solution that we are looking forward to bringing to farmers," Dow's Joe Vertin told Reuters.

More than 140 advocacy groups have participated in a letter writing campaign calling on U.S. Agriculture Secretary Tom Vilsack to reject Dow's regulatory application for the herbicide and herbicide-resistant crops, submitting more than 365,000 missives ahead of a public comment period that ends April 27.

"The scientific community has sounded alarms about the dangers of 2,4-D for decades," wrote opponents in their letter to Vilsack. "Numerous studies link 2,4-D exposure to major health problems such as cancer, lowered sperm counts, liver toxicity and Parkinson's disease. Lab studies show that 2,4-D causes endocrine disruption, reproductive problems, neurotoxicity, and immunosuppression."

Some farmers have argued that the new herbicide, a combination of 2,4-D and glyphosate -- the active ingredient in Monsanto's bestselling Roundup weed killer -- is necessary to combat weeds that have become resistant to glyphosate alone.

2,4 d is a extremely common weed killer. It has been in general use for 65 years. The common uses are for weed control in crops and lawns. I would guess 90% of the homes in the US have it the garage. However, it is toxic and should be handled with proper care.

While it was used in the agent orange mixture, the inclusion of that in this story is more of an attempt at alarm-ism and exaggeration than to inform.